I want to get basic information from a hard-drive and print it out. The most important is that the physical sector size is correct.
For the past few hours I have been fighting with ioctl to get what I want but I can't figure it out.
I have never used ioctl before and I can't seem to find an easy explanation on what exactly you have to do.
Anyway my code looks something like this
int main () {
FILE *driveptr;
int sectorsize;
struct hd_driveid hd;
driveptr=fopen("/dev/sda","r");
if (ioctl(driveptr,HDIO_GET_IDENTITY, &hd)!=0) {
printf("Hard disk model: %s\n",hd.model);
printf("Serial number: %s\n",hd.serial_no);
printf("Sector size: %i\n",hd.sector_bytes);
sectorsize=hd.sector_bytes;
} else {
printf("Error fetching device data.\n");
}
}
In the compiler it throws these warnings, it compiles but the strings are empty when printed.
gcc -o test source.c
source.c: In function ‘main’:
source.c:67:9: warning: passing argument 1 of ‘ioctl’ makes integer from pointer without a cast [enabled by default]
/usr/include/x86_64-linux-gnu/sys/ioctl.h:42:12: note: expected ‘int’ but argument is of type ‘struct FILE *’
I hope somebody can explain to me what goes wrong!
Instead of
if (ioctl(driveptr,HDIO_GET_IDENTITY, &hd)!=0) {
you probably want
if (ioctl(fileno(driveptr),HDIO_GET_IDENTITY, &hd)!= -1) {
^^^^^^^ ^ ^^
Because ioctl's first argument need to be an integer file descriptor not a FILE *
fileno() will give you an integer fd from a FILE *.
Note also that ioctl returns -1 on an error and sets errno.
Reading the man pages of the functions you are using is probably quicker than posting to StackOverflow.